Conventionally, a vehicle vibration suppression control device is known that includes: a feedforward compensator Gm(s)/Gp(s) consisting of a transmission characteristic Gp(s) which is linearly approximated control target and a model response Gm(s); a motor angular velocity estimation unit that inputs a final torque target value and that uses the transmission characteristic Gp(s) which is the control target to estimate a motor angular velocity; and a feedback torque computation unit that calculates a feedback torque by inputting a deviation between a motor angular velocity estimation value and a motor angular velocity detection value into a filter H(s)/Gp(s) consisting of the inverse characteristic of the transmission characteristic Gp(s) which is the control target and a bandpass filter H(s) (see JP2003-9566A). The feedforward control and feedback control system described above is formed, and thus when there is no lag element in the control system, it is possible to obtain an ideal vehicle response intended by a designer to a torque instruction value and disturbance.
However, in an actual control device, there are a time lag caused by a control computation time, a motor response lag and a time lag caused by a time necessary for the detection and processing of signals with various sensors. Hence, even in a state where no disturbance is present, a phase difference is produced between a motor angular velocity estimation value and a motor angular velocity detection value, and thus an unnecessary feedback torque is produced, with the result that an actual vehicle behavior does not agree with a model response.
In order to solve this problem, a vehicle vibration suppression control device disclosed in JP2005-269835A uses, instead of a bandpass filter H(s), Hc(s) in which the center frequency and the gain of the bandpass filter H(s) are adjusted, and thereby removes a phase displacement in the feedback torque.